# GNU General Public License (GPL) The GNU General Public License (GPL) is a copyleft free software license created by [[Richard Stallman]] for the [[GNU is not Unix (GNU)|GNU]] project. First released in 1989, the GPL ensures that software remains free by requiring derivative works to be distributed under the same license. It's the most widely used free software license, covering the Linux kernel, GCC, and thousands of other projects. The GPL's key innovation is "copyleft"; using copyright law to ensure freedom rather than restrict it. Unlike permissive licenses ([[MIT License]], [[BSD License]]), the GPL requires that modified versions also be open source, preventing proprietary forks. This "viral" nature is controversial in business contexts but ensures software freedom propagates. ## GPL Versions | Version | Year | Key Changes | |---------|------|-------------| | GPLv1 | 1989 | Original release | | [[GPLv2 License]] | 1991 | Added "Liberty or Death" clause | | [[GPLv3 License]] | 2007 | Patent protection, anti-Tivoization | ## Core Requirements - **Source code**: Must be made available - **Copyleft**: Derivatives must use GPL - **No additional restrictions**: Cannot add proprietary terms - **License notice**: Must include GPL text ## GPL Family - **GPL**: Strong copyleft for applications - **LGPL**: Allows proprietary linking (libraries) - **[[Affero General Public License (AGPL)]]**: Extends to network services ## Notable GPL Projects - Linux kernel (GPLv2) - GCC, GDB, GNU Coreutils - WordPress, Drupal - GIMP, Inkscape ## References - https://www.gnu.org/licenses/gpl-3.0.html - https://en.wikipedia.org/wiki/GNU_General_Public_License ## Related - [[Richard Stallman]] - [[Free Software Foundation (FSF)]] - [[GPLv2 License]] - [[GPLv3 License]] - [[Affero General Public License (AGPL)]] - [[Open Source]] - [[Free and Open Source Software (FOSS)]]